Method of forming small apertures in thin metal plate-shaped articles



Feb. 19, 1957 w. F. BLADERGROEN ET AL 2,781,849

METHOD OF FORMING SMALL APERTURES IN THIN METAL PLATE-SHAPED ARTICLESFiled Jan. 29, 1955 2 Sheets-Sheet 1 IN VEN TORS WILLEM FREDERIKBLADERGROEN KAREL JAN PERK AGENT Feb. 19, 1957 w. F. BLADERGROEN ET AL2,781,849

MET OF NG LL APERTURES IN T ME ATEI- APED ARTICLES Filed Jan. 29, 1953 2Sheets-Sheet 2 IN VEN TORS WILLEM FREDERIK BLADERGROEN KAREL JAN PERKAGENT United States Patent METHOD OF FORMING SMALL APERTURES IN THINMETAL PLATE-SHAPED ARTICLES Willem Frederik Bladergroen and Karel JanPerk, Dordrecht, Netherlands, assignors to The Hartford National Bankand Trust Company, Hartford, Conn., as trustee Application January 29,1953, Serial No. 334,054

Claims priority, application Netherlands March 25, 1952 v 2 Claims. (Cl.164-125) When thin plate-shaped articles made of compara tively hardmaterials, such as steel, more particularly stainless steel, are to beprovided with apertures of small diameter, for. example of the order offrom 0.2 to 0.4 mm., the usual methods are found to give rise inpractice to serious diiiiculties. Breaking of the drills often occursand it has been found that even increasing the speed of the drillingspindle to high rates (for example 12,000 revolutions per minute) doesnot result in appreciably reducing these difliculties. Thesedisadvantages are particularly manifest, when apertures are required tobe made with a conical profile and also when the article is made ofstainless steel. the problem arises that during drilling the materialhardens increasingly under the point of the drill.

The invention provides a solution of this problem by using a punch on amandrel which is pressed into the article tobe provided with anaperture, special measures being taken to prevent breaking or crackingof the material of the article.

The method according to the invention of providing a small aperture in athin metal plate-shaped member is characterised in that a metal disk isarranged on a noncompressible plastic rnass, such as rubber, which issurrounded by a rigid rim in a manner such that the central part of thedisk rests upon the plastic material and that the edge of the disk restsupon the rigid rim surrounding the mass, and in that at least oneadditional metal disk is arranged on the said disk and that thearticleto be provided with an aperture is arranged on the uppermostdisk, the article and the disks all having thicknesses of the same orderand the adjacent surfaces of these disks and of the article preferablybeing provided with a small amount of lubricant. A mandrel having apreferably conical point or punch is then pressed into the surface ofthe article to be apertured so as to provide a through-hole after thesurface of the article more remote from the mandrel, is subjected,iflrequired, to a shaving operation.

When the point of the mandrel engages with the upper surface of thearticle it penetrates into the article through a small distance withoutappreciable deforma tion of the latter. However, as soon as the point orpunch has obtained sufficient pressure area in the article the latter.tendstto become plastically deformed while being guided by the disksarranged beneath it In these cases and by the plastic material providedunder the under- When said bulge is removed by a shaving operation,

However, according to the invention, as an alternative, the point of themandrel may be pressed into the material of the article so far as toproduce a throughhole in the material of thearticle. Such aperturewillgenerally be wider than in the use of the above-mentioned method wherebythe aperture in the article is not formed until after the local bulge onthe surface of the article is removed by a shaving operation.

The method according to the invention lends itself particularly for theformation of substantially tapering apertures having diameters of from0.02 to 0.6 mm. in articles of low thickness, that is to say a thicknessless than 5 mms., and made of hard material, such' as steel, moreparticularly stainless steel. As found according to the invention, thisensures a method of manufacturing which can be carried out by simplemeans and the results of which are found to be always satisfactory.Results differing in accordance with the choice of the material of thewashers and of their thickness may be achieved by means of the samepress. As mentioned hereinbefore, the thickness of the washers will bemade of the same order as the thickness of the articles but the diameterof these plates must exceed the diameter of the article, since thisenables the washers to envelop,

as it were, the article at its edge during the plastic deformation ofthe article. Plate-shaped waste material may suitably be used asmaterial for the washers, the only requirement to be satisfied by thismaterial being that at the obtaining pressures it should be enabled byits ductility to assume the required deformation. The invention will nowbe described with reference to the accompanying diagrammatical'drawing,given by way of example, in which: i

- Fig. 1 is a longitudinal sectional view of adevice for carrying outthe method according to the invention and shown in a position in whichthe mandrel is at some distance above the article to be provided with anaperture.

Fig. 2,is a longitudinal sectional view of the same device,themandrel,however, occupying a position in which it has been substantiallypressed through thear ticle to be provided with an aperture.

Figs. 3, 4 and 5 show three successive stages of an' article, themandrel not being pressed entirely through the article, but beingretracted at the moment at which a bulge'of the material is produced onthe surface of the article more remote from the'mandrel (Fig. 3), saidbulge having been ground oif in Fig. 4, whereas in the stage shown inFig. 5 the apertureprovided in the stage shown in Fig. 4 has beenreamed. 1

Fig. 6 shows an embodiment of an article in which the aperture isproduced by pressing the mandrel so far into the article that its pointhas left the article on'the opposite side. Fig. 7 is a longitudinalsectional view of'a nozzle for use in a burner, the mouthpiece of thenozzle being I constituted by the object shown in Fig. 5.

The device according to Figs. 1 and .2 coinprise s. a. thickwalled metalpot 2 which 'is arranged on a table 1 and contains a supply 3 ofplasticnon-compressible material, the material being rubber in the caseshown.

As may be seen from Fig. l the upper surface of the 3. mass 3 is in thesame plane as the upper rim if of the pot 2. The surface of this masshas a disk 5 about 1.2

mm. in thickness arranged on it in a manner such that the edge of thedisk rests upon the upper 11111 4: of the pot whereas the central partof the disk is supported upon the material 3. This disk" has twoadditional superposed disks 6 and 7 arranged on it both of which haveapproximately the same thickness as the disk 5 A steel plate 8 which isto be provided with an aperture and has a thickness of approximately 1.5mm. is arranged on the upper surface of the disk, and, as may be seenfrom-the figure, has an appreciably smaller diameter than the disks S,6, and 7. Arranged over the article ii is a mandrel 9 which has aconical point or punch 10 and is secured in a hand press (not shown)When the mandrel 9 is lowered, as indicated in Fig. 2, the punch ofthemandrel will initially penetrate into the material of the articlethrough a small distance without appreciable plastic deformation of thearticle 8. On further movement of the punch 10 of the mandrel 9 theplate tends to become plastically deformed and is thus embossedconically, as may be clearly seen from Fig.1, The disks 7, 6 and 5 willthus also become de} formed, all of them assuming a more or less conicalshape. The fact, that the materialenclosed between the reverse side ofthe article 8 and the sur'face of the rubber mass 3 is Stratified due tothe disks 7, 6 and 5 permits of the layers sliding relatively during thepressing operation. This allows deformation of this intermediatematerial without cracking or breaking and thus enables' the intermediatematerial to protect the article to be apertured against breaking orcracking. As may be seen particularly from Fig. 2, the material of thedisk 7 envelops as it were the edge of the article 8 during itsdeformation. 7

During the plastic deformation of the disk 5 the upper surface of themass 3 is also conically forced in, but owing to the fact that thismaterial, though plastic, is not compressible the more outward parts ofthe supply of rubber} rise so that the bottom of the disk 5 invariablyfinds sufficient support throughout its surface.

Theedge of the disk 5 which originally rested on the upper rim 4 of themetal pot 2 to find sufilcient support during the lowering of thepunch,-- becomes gradually detached from this rim, as may also be seenfrom Fig. 2, so that at; the termination of the pressing operation thebottom of the edge of; the disk 5 becomes located at a short distanceabove the upper rinr4 of the metal pot 2. To enable the material of thearticle and of the disks to become deformed under the action of thepressing power it is advantageous for the pressing s peed to below. i tV When the pressing operation is stopped the punch 9 is raised ,and thearticle 8 may be removed from the press. The disks 5, 6 and 7 aresubsequently removed. The upper surface of the rubber material 3 hasresumed its flat shape immediately upon release of the pressure, newdisks are placed in position, a. new article is arranged on the disk 7and pressing may restart,

With respect to the machining operations of the, article shown in Figs.3, 4 and 5 the following should be noted. As may be seen from Fig. 3,the article 12 shown in this figure exhibits a more or less conical:shape comprising centrally .the depression 13 caused by the conicalpoint 10 of the mandrel. The top of ;this;aperture lies in a plane X--Xindicated in Fig. 4. Under this plane there is a localbulge of material14.

At the stage shown in Fig. 4.this bulge 14 has been removed by a shavingoperation, forexample, by grinding the article 12, a very narrowaperture 15 being thus formed in the plane X-X. This aperture isgenerally too small for practical use. 1

Hence, as may be seen" from Fig. 5, this aperture is reamed by means ofa thin dilll so as to form a cylindrical aperture 16, the diameter d ofwhich may be chosen in accordance with the requirements to be satisfied.In contradistinction to the case mentioned in the first few paragraphshereof, reaming the aperture already provided is not beset withdifiiculty, since the core of the drill is not required to do any work.The diameter d of the reamed hole may be very small, for example, 0.05mm, but obviously appreciably greater as an alternative, in accordancewith the use of the apertured article.

In the embodiment shown in Fig. 6 the article has an aperture 21 formedin it being pressed by the point 10 of the mandrel 9 throughflthematerial of the article 23 to such an extent that during the pressingoperation the point 10 of the mandrel has disengaged from the article28" at the reverse side. Also in this case the di-' ameter air may bevariable in accordance with the requirements to be satisfied. The methodillustrated in Fig. 6 will generallybe chosen to form apertures ofslightly greater size, for example of the order of from 0.3 to 0.6 mm.Any burrs that may be left at the lower edge of the aperture 21 afterthisaperture is pressed can readily be removed by the usual means.

The nozzle shown in Fig. 7 for use in a burner comprises a cylindricalcase 30 which at the end 31 is threaded to enable the nozzle to besecured in a support. The case 30 comprises in its bottom part aconically tapering stop surface 32 which fits the apertured article 34.This article-34 acts as a nozzle with the aid of the aper ture 33 formedin it. After the conical outer edge (visible in Figs. 3 to 6) of thearticle 34 is removed and a cylindrical outer surface has thus beenproduccd the article is secured internally of the case 30 by means of apressed-in cylindrical sleeve 35.

What we claim is:

l. A method of forming small apertures in a thin metal, plate-shapedarticle comprising placing a noncompressible plastic mass in a metalreceptacle, positioning a metal disk having the periphery of a surfacethereof abutting said metal receptacle and another portion of saidsurface abutting said plastic mass, arranging said plate-shaped articleon said metal disk, said article.

and said -diskhaving thicknesses of the same order, pressing a punchinto a surface of said. article, to thereby form a smallthrough-aperture in said article and shape said article conically.

2. A method of forming small apertures in a thin metal, plate-shapedarticle comprising placing a noncompressible plastic mass in a metalreceptacle, positioning a metal disk having the periphery of a surfacethere of abutting said metal receptacle and the remainder of saidsurface abutting said plastic, mass, arranging said plateshaped articleon said metal disk, said article and said disk having thicknesses of thesame order, forcing a punch through said article to thereby forma smallthrough-aperture therein.

References Cited in the file of this patent UNITED STATES PATENTS

